Women who shop may have a deeper motivation than simply looking good, they may be trying to hold onto their man.

A study of 649 women revealed they may purchase designer clothing and handbags to keep other women from stealing their boyfriend or spouse, a University of Minnesota press release reported.

"It might seem irrational that each year Americans spend over $250 billion on women's luxury products with an average woman acquiring three new handbags a year, but conspicuous consumption is actually smart for women who want to protect their relationship," Carlson School of Management Associate Professor Vladas Griskevicius, said.  "When a woman is flaunting designer products, it says to other women 'back off my man.'"

The researchers studied what women thought about other peoples' relationships based on their material possessions.

"We found that a woman who is wearing luxury items and designer brands is perceived to have a more devoted partner and as a result other women are less likely to flirt with him," Yajin Wang, a PhD student who participated in the study, said. "Regardless of who actually purchased the items, other women inferred that the man had something to do with it and is thus more devoted to her."

Another study by the same researchers attempted to make women feel jealous by asking them to imagine another women flirting with their partner. Later on they were asked to draw a designer label on a handbag, without realizing how it was related to the experiment.

Women who had recently experienced jealousy drew a label twice as large as those who had not.

"The feeling that a relationship is being threatened by another woman automatically triggers women to want to flash Gucci, Chanel, and Fendi to other women," Wang said. "A designer handbag or a pair of expensive shoes seems to work like a shield, where wielding a Fendi handbag successfully fends off romantic rivals."

The team also found women who felt their relationship was threateded were 32 percent more likely to put their own money towards a chance of winning an elaborate shopping spree.

Past studies by Griskevicius concluded men bought expensive items to impress women and attract them as mates, this study found females also buy to impress women.

"The fact that most women's luxury products are aimed to impress other women helps explain why men have a hard time figuring out if a woman's handbag costs $50 or $5, 000," Griskevicius said. "Women's designer products are geared to show off to other women not men."

This effect was seen not only in those committed to a relationship, but in single women as well.

 "Many single women obviously want designer products, but instead of these products saying back off my current man, the single woman is saying back off my future man," Wang said.